Akonadi-googledata allows you to syncronize Akonadi with your Google
calendar and contacts.

Passwords will be stored in KWallet, for while only 1 account is
allowed. For hosted accounts (i.e. joe.bar@whatever.com), just input
the whole username plus server name in configuration dialog (i.e.
joe.bar@whatever.com). For normal google accounts (i.e. joe@gmail.com),
just the username is required (i.e. joe).

Only the main calendar is supported.

Recurrent events are not supported, the reason: Google uses an
invalid iCal inside of the XML to represent recurrence).
http://code.google.com/apis/calendar/data/2.0/developers_guide_protocol.html#CreatingRecurring
